For the displacement of air at standard, ambient or normal atmospheric pressure, mechanical means are practically exclusively used today although a number of physical phenomena are known to be effective in the displacement of gases.
For example, it is known to pump gases by adsorption processes, by cooling and heating processes, by diffusion processes and by the use of electric fields or charges in a so-called electric wind or static breeze processes or in accordance with the principles thereof (see Bergmann-Schaefer, Vol. 2, pp. 10-474). At atmospheric pressures, however, these processes have found little utility to date and the concentration has been upon the use of mechanical blowers with impellers or rotors or on the use of water jet pumps.
For higher pressures, both rotary and linearly reciprocating mechanical devices may be used and for reduced pressures the concentration is upon the use of adsorption pumps of various constructions, ion-getter pumps, diffusion pumps, cryopumps and the like. Electric wind has also been utilized at reduced pressures, generally in the range between so-called pre-vacuums and high vacuums for gas transport as described, for example, in German Pat. No. 265,534.
In general, the mechanical systems used at atmospheric pressure or above for the displacement of air are noisy and of low energy efficiency while the techniques utilized for the displacement of gas at low pressures have seldom been considered effective at atmospheric pressure or for the high volume displacement of gases such as air.